Known millimeter wave oscillators generally use high frequency devices such as Gunn or IMPATT diodes which oscillate in metal cavities. In the frequency range from about 35 GHz to about 300 GHz, there are applications for oscillators used in receiver and transmitter communication devices and in radar units. These applications of such oscillator devices, it may be generally stated, involve the use of low power. The high operating frequencies and related short wavelengths of the outputs require extremely precise construction of the oscillator physical entities. Machining for the parts of such devices and apparatus is extremely costly, which limits the practical applications wherein the use of the devices is economically feasible.
In order to benefit from the relatively high stability of the mechanically tuned units such Gunn diode oscillators and IMPATT diode oscillators because of their mechanical adjustment and setting features, a disideratum would be to provide some ancillary type of adjustment which could fine-tune the oscillator component without disturbing its basic mechanical setting or mechanically set frequency in a resonating cavity.
With this, then, being the state of the art, we conceived and developed our invention with the primary objective providing a fine-tuning ancillary component to the basic mechanically tuned and set oscillator devices.
A further and important object of the invention is to provide an adjustably tuneable millimeter wave source which has substantially rugged, inexpensive, and readily replaceable components.
A still further object of the invention is to provide the combination according to our concept and development with discrete and replaceable elements being readily and commercially available without the need for specialized manufacture, fabrication or assembly.
The invention, then, provides a compact, low cost, mechanically tuneable Gunn oscillator with additional electronic tuning through the use of a coupled and operably assembled varactor diode. By changing the bias on the varactor diode through electronic circuitry, the basic or set range of the Gunn oscillator can be fine tuned with hitherto unattainable precision and accuracy to frequencies within useful ranges on either side of the Gunn diode set point frequency.